1. Field of the Invention
This invention relates to treatment of fluids and particularly to the use of a magnetic field for the treatment of fluids.
2. Prior Art
Many publications concerning magnetic phenomena have appended covering a broad range of subjects related to such diverse topics as theories and experiments on the magnetic properties of materials, applications involving these materials, nuclear magnetic resonance, etc. However, relatively little formal theory has been developed to explain reaction of fluids to magnetic fields disclosed in the patent literature. The devices and techniques disclosed in the patent literature have been developed on an empirical basis.
U.S. Pat. No. 4,201,140 to Robinson is for a chamber that houses a magnetic array through which fluid is circulated. U.S. Pat. No. 4,933,151 is for an array of disk (circular) magnets having a central hole through which fluid passes in the axial direction of the magnets. Neither arrangement can be adapted to the outside surface of an existing career. ("Carrier" in the context of this specification means conduit or tank.)
U.S. Pat. No. 4,605,498 to Kulish discloses magnetic treatment of liquids by concentrating "primarily south pole magnetic fields on the liquids to provide descaling and deliming properties thereto". The apparatus generally comprises a cylindrical structure of molded plastic surrounding a pipe through which a liquid is passed. The casing contains plural magnets arranged around the periphery of the pipe in such a manner that their north poles are directed radially outward from the central axis of the pipe and their south poles are directed radially inward toward the axis of the pipe in order to concentrate the south pole magnetic fields more strongly on the fluid.
The general treatment of magnetostatics is presented in numerous texts to which the reader is referred. (See, e.g., Principles of Electricity and Magnetism by G. P. Hamwell, McGraw Hill, 1938) However, the highlights of the theory which bear on this specification are presented as follows:
A magnetic circuit is analogous to an electric circuit and since there may be more familiarity with an electric circuit, it is useful to present the analogy. In an electric circuit, the applied voltage, V, generates an electric current, I, in series connected resistances, R1, R2, - - - Rn, according to the relation: EQU V=I(R1+R2+- - - Rn)
Each resistance, Rn, of a region of the circuit having a length, L, cross sectional area, A, and resistivity, r, is given by: EQU Rn=rL/A
Analagously (see FIG. 7), in a magnetic circuit comprising a permanent magnet 14 generating a magnetic flux 16 around a continuous path consisting of regions 18, 20, of various lengths, cross sectional areas and magnetic permeabilities:
magnetizing force, pLA, is analogous to voltage, V, (where p is the polarization, L is the length of the magnetized body, and A is the cross sectional area of the magnetized body); PA1 total flux, .phi. is analogous to electric current, I; PA1 reluctance, P, is analogous to resistance, R. Thus, the reluctance, P, of each region is: EQU P'"=L'"/A'"u'"
u'" is the magnetic permeability of the region, A'" is the area, L'" is the length.
Therefore, EQU pLA=.phi.(P'+P"+- - - Pn) EQU But, EQU .phi.=B'A'=u'H'A'
where B' is flux density in the region of area A', H' is the magnetic field in the region, u' is the permeability of the region.
Therefore, the magnetic field, H', in region A' is EQU H'=pLA/A'[P1+P2+- - - Pn]u'
Another approach to calculating field intensity is to treat a permanently magnetized medium as mathematically equivalent to replacing the body by a surface charge. For example, FIG. 2 shows an ellipsoid 22 that is uniformly magnetized as indicated by the (+-) dipoles. FIG. 3 shows the mathematical equivalent in which the body dipoles shown in FIG. 2 have been hypothetically replaced by equivalent surface charges 24 in FIG. 3. This substitution reduces the problem of calculating the field intensity generated by the polarized ellipsoid of FIG. 2 to finding the potential function, V, of the surface charge of FIG. 3 and equating the magnetic field to the gradient of V. This approach is explained in a number of texts particularly as applied to situations where conditions are constant in one direction (the "z" coordinate) thereby reducing the problem to finding a potential function dependent on only two coordinates, r, and .theta.. (See FIG. 4) For example, V(r,.theta.) for a line charge q parallel to the z axis located at r',.theta.', EQU V(r, .theta.)=2q (r/r') [cos n.theta.'cos n.theta.+sin n.theta.'sin n .theta.]/n 1./
(W. R. Smythe, Static and Dynamic Electricity, Mcgraw Hill, 1939)
The effect of positioning a pole piece on the charged surface is to transfer the charge from the surface of the magnetized body to the fartherest surface of the pole piece. This is illustrated in FIG. 5 showing a uniformly magnetized horseshoe magnet with surface charges + and - compared to FIG. 6 showing the horseshoe magnet 26 with pole pieces 28.
The point of the foregoing remarks in relation to this specification is to emphasize that a magnetic field imposed within a pipe by a magnetic array will be determined not only by any north or south poles placed in the immediate vicinity of the pipe wall, but also by the shapes and properties of the parts that make up the entire magnetic circuit.